Sudden rash

This isn't my June baby but my 4 month old, this morning it was a bit darker just on her forehead/eye area but after a short nap it went down considerably for the rest of the day.

We just took her out of the bath and now I can clearly see it everywhere, smooth not bumpy and doesn't really seem to be bothering her. I'll be calling the pediatrician in the morning but just wondering if anyone has had this before? It kind of looks like the same rash my 2 year old had with roseola but this baby didn't have a fever 🤔